What is the least common multiple of 27 and 21? Another way to say this is: $\lcm(27, 21) = {?}$
Solution: The least common multiple is the smallest number that is a multiple of 27 and 21. We know that 27 x 21 (or 567) is a common multiple, but is it the least common multiple? Write out the multiples of 27 until we find a number divisible by 21. 27, 54, 81, 108, 135, 162, 189, So, 189 is the least common multiple of 27 and 21.